Preparation of Large Pore Silicas and Uses Thereof in Chromium Catalysts for Olefin Polymerization

A supported chromium catalyst comprising a silica composite and from about 0.1 to about 15 wt. % chromium, wherein the catalyst is characterized by:

• a bulk density from about 0.08 to about 0.4 g/mL;
• a total pore volume from about 0.4 to about 2.5 mL/g;
• a BET surface area from about 175 to about 375 m2/g;
• and
• a peak pore diameter from about 10 to about 80 nm.

A process for preparing a silica composite, the process comprising:

• (1) combining silica component I and silica component II in a diluent comprising at least about 70 wt. % water to form a mixture;
• and
• (2) forming the silica composite in the mixture;
• wherein:
• silica component I comprises irregular and non-spherical silica particles characterized by an average aspect ratio of at least about 2:1 and a BET surface area in a range from about 150 to about 1000 m2/g;
• silica component II comprises a colloidal silica;
• and
• the silica composite is characterized by:
• a bulk density from about 0.08 to about 0.4 g/mL;
• a total pore volume from about 0.4 to about 2.5 mL/g;
• a BET surface area from about 175 to about 375 m2/g;
• and
• a peak pore diameter from about 10 to about 80 nm.

A process for preparing a silica composite, the process comprising:

• (1) combining silica component I and silica component II in a solvent to form a mixture;
• and
• (2) forming the silica composite in the mixture;
• wherein:
• silica component I comprises a fumed silica;
• silica component II comprises a silicon compound;
• and
• the silica composite is characterized by:
• a bulk density in a range from about 0.08 to about 0.4 g/mL;
• a total pore volume from about 0.4 to about 2.5 mL/g;
• a BET surface area from about 175 to about 375 m2/g;
• and
• a peak pore diameter from about 10 to about 80 nm.